
where \(\pi \)  is the second fundamental form and \(h_{ij}(0)\)  are its
coefficients, \(\bar{R}_{ikjl}(0)\)  and \(R_{abcd}(0)\)  are the curvature
tensor of \(\partial M\)  and \(M\) , respectively, \(\bar{R}_{ij}(0)=\bar{R}_{ikjk}(0)\) 
are the coefficients of the Ricci tensor, and \(\operatorname{Ric_{\eta }}(0)=R_{nini}(0)=R_{nn}(0)\) 
(see [1]}).
